Husqvarna 325HS99X-series manual Maintenance, Carburettor

MAINTENANCE

Carburettor

Your Husqvarna product has been designed and manufactured to specifications that reduce harmful emissions. After the engine has used 8-10 tanks of fuel the engine will be run-in. To ensure that it continues to run at peak performance and to minimise harmful exhaust emissions after the running-in period, ask your dealer/ service workshop (who will have a rev counter at their disposal) to adjust your carburettor.

WARNING! The complete clutch cover

! and gear housing must be fitted before the machine is started, otherwise the clutch may come loose and cause personal injury.

Function

•The carburettor governs the engine’s speed via the throttle control. Air and fuel are mixed in the carburettor. The air/fuel mixture is adjustable. Correct adjustment is essential to get the best performance from the machine.

•Adjusting the carburettor means that the engine is adapted to local operating conditions, e.g. climate, altitude, petrol and the type of 2-stroke oil.

•The carburettor has three adjustment controls: L = Low speed jet

H = High speed jet

T = Idle adjustment screw

L H T

•The L and H-jets are used to adjust the supply of fuel to match the rate that air is admitted, which is controlled with the throttle. If they are screwed clockwise the air/fuel ratio becomes leaner (less fuel) and if they are turned anti-clockwise the ratio becomes richer (more fuel). A lean mixture gives a higher engine speed and a rich mixture gives a lower engine speed.

•The T-screw regulates the throttle setting at idle speed. If the T-screw is turned clockwise this gives a higher idle speed; turning it anti-clockwise gives a lower idle speed.

16 – English

Basic setting

•The basic carburettor settings are adjusted during testing at the factory. The basic setting is richer than the optimal setting and should be maintained for the first few hours the machine is in use. The carburettor should then be finely adjusted. Fine adjustment should be carried out by a skilled technician.

CAUTION! If the blades move while the engine is idling the T screw should be turned anti-clockwise until they stop.

Rec. idle speed: 2700 rpm

Recommended max. speed: See the Technical data section.

WARNING! If the idle speed cannot be

! adjusted so that the cutting attachment stops, contact your dealer/service workshop. Do not use the machine until it has been correctly adjusted or repaired.

Fine adjustment

•When the machine has been ”run-in” the carburettor should be finely adjusted. The fine adjustment should be carried out by a qualified person. First adjust the L- jet, then the idling screw T and then the H-jet.

Conditions

•Before any adjustments are made, make sure that the air filter is clean and the air filter cover is fitted. If you adjust the carburettor when the air filter is dirty it will result in a leaner mixture when the filter is finally cleaned. This can lead to serious engine damage.

•Carefully turn both jets, L and H, so that they are midway between fully screwed in and fully screwed out.

•Do not attempt to adjust the L and H jets beyond either stop as this could cause damage.

•Now start the machine according to the starting instructions and let it warm up for 10 minutes.

CAUTION! If the blades move while the engine is idling the T screw should be turned anti-clockwise until they stop.